A hybrid vehicle has a regenerative braking function that provides not only braking force but electricity to charge a battery by generating a predetermined amount of reverse torque in a motor generator in braking.
On the other hand, in a vehicle equipped with an automatic transmission, as the vehicle speed decreases, gearshift is performed from the present N-state to an N−1-state.
Accordingly, in a vehicle equipped with a hybrid driving apparatus including an automatic transmission, in a pre-stop state in which a driver releases the acceleration pedal and presses down the brake pedal for deceleration, a considerable amount of reverse torque is exerted in the input shaft of the automatic transmission for generative braking and pre-stop gearshift (i.e., N to N−1 shift).
However, when the pre-stop gearshift is performed with the considerable amount of reverse torque exerted in the input shaft of the automatic transmission as described above, the input shaft may reverse while the clutch inside the automatic transmission slides.
In the above case, it is difficult to control the desired gearshift and a desired driveablity cannot be ensured. Further, the oil pump in the automatic transmission may be reversely operated, such that it does not supply oil into the automatic transmission, but pumps the oil out of the automatic transmission. Therefore, friction members in the automatic transmission may be damaged and the automatic transmission may even fail or be broken.
The above information disclosed in this Background Art section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.